Dark matter is the mysterious non-luminous substance that makes up most of the vast expanse of the universe.
Although experts have been observing the gravity effects of dark matter for decades, its true nature has yet to be understood.
Who discovered dark matter?
At the end of the nineteenth century, astronomers began to speculate about invisible matter, which is the dying stars or the gas and dust in the universe. Researchers have even begun to estimate their mass. Most of them think that this mysterious matter makes up a small part of the total mass of the universe.
It wasn’t until 1933 that the Swiss-American astronomer Fritz Zwicky noticed that distant galaxies always revolved around each other much faster than they should, since their matter could be observed. through the telescope. If this were confirmed, he said, we would have the surprising result that there is much more dark matter than light matter.
But many researchers in the field remained skeptical of Zwicky’s results until the 1970s, when astronomers Kent Ford and Vera Rubin conducted detailed studies of stars in regions of the world. outside our neighbor Andromeda galaxy. These stars orbited the galaxy’s core extremely quickly, as if some invisible matter had a gravitational pull pulling on them and pushing them along – a phenomenon that scientists soon discovered. found to occur in all galaxies throughout the universe.
The researchers did not know what the invisible mass contained. Some speculate that dark matter is made up of small black holes or other solid objects that emit so little light that they are barely visible with a telescope. In the 1990s, observations became even more bizarre, when a telescope called the Wilkinson Microwave Anisotropy Probe (WMAP) showed this dark matter to be up to five times heavier than normal matter.
Why is dark matter still a mystery?
Telescope surveys never seem to be able to find enough tiny solid objects to account for such a vast amount of dark matter. Most astronomers today think that dark matter is composed of subatomic particles with properties much different from the protons and neutrons we know.
The strongest candidate for dark matter is known as the weakly interacting massive particle (WIMP). These speculative entities are not found in the Standard Model of particle physics, a model that describes most particles and forces. WIMP may be more like a ghost neutrino, except it is 10 to 100 times heavier than a proton. (The exact mass of neutrinos is unknown, but they are much lighter than electrons.)
Like neutrinos, WIMP only interacts with two of the four fundamental forces in the universe, gravity and the nuclear weak force. These dark matter particles do not interact with electromagnetism, the basis of light, and will therefore remain invisible at all times.
Physicists have built giant detectors and placed them deep underground to protect them from cosmic rays in order to search for WIMPs, but so far no experiments have found proof of them. In recent years, this failure has led some researchers to begin to question whether we are chasing a seed in the wild, but the search never ends.
For the same reason, some scientists have turned to a newer dark matter candidate called an axion, a particle millions or even billions of times smaller than an electron. These speculated particles are particularly attractive to researchers because they can also solve another difficult problem in physics, that is, they may well interact with neutrons to explain why they are perceived magnetic field but not electric field.
In June 2020, scientists at the Gran Sassco National Laboratory, Italy, announced that they had stumbled upon a small signal that could be explained by the axion. These results have shocked the scientific community, but have not been confirmed by other experiments.
Is dark matter real?
When asking this question, researchers are still scratching their heads just to answer what dark matter is. Some theorists wonder if there is a completely dark part of the universe, with a wide variety of particles and even with dark forces acting only on dark matter, like the complexity of the subatomic world.
At the same time, a small number of scientists believe that dark matter is an illusion. They cite an idea called a modified version of inertia (MOND), an idea that conjectures that on a large scale, gravity works differently than we thought and this explains the rotation of stars and galaxies. But most experts don’t see the need to start with such an idea so far removed from ordinary physics, because if we did, we would have to change our understanding of much of the already proven reality.
Dark matter is not related to dark energy, another mysterious phenomenon that causes the universe to rapidly expand. These two concepts share the same word “dark” often used by scientists to refer to things and phenomena that they do not fully understand.